Gear Introduction

Gears are the optimal medium for low energy loss, high accuracy and low play, for high-speed machinery such as an automobile transmission.

To understand the gear you have to understand the lever function. The lever and fulcrum make up a simple machine where a stiff beam (the lever) rotates about a fixed pivot (the fulcrum).

The diagram to the right shows a little longer lever. You will notice side "A" is equal to side "B". Or the input force equals the output force. But notice that side "B" is longer than side "A". Therefore the output force will be larger. This is a ratio of output force to input force called mechanical advantage.

The Wheel
Although they may seem very different, wheels and gears are closely related to levers. The wheel is essentially a rotating lever. Think of the diagram of the lever above as being bent into a circle. The center of the circle is the fulcrum. In math we call this the center point.

Wheel "A" is a circle. It is larger than wheel "B". The black circle. You will notice that "A" is larger than "B". The diameter of "A" is larger than "B". If you rotate "B"(the axle) it will move wheel "A". Since "B" is smaller than "A" and moves in a smaller circle than "A" you will use very little input you get a large output. The large ratio of the wheel radius to the axle radius is what makes it easy to turn the wheel at it's rim.